Molecular weight determination of Kraft lignin samples by Size Exclusion Chromatography
(2021) KASM01 20202Centre for Analysis and Synthesis
- Abstract
- The valorization of lignin offers sustainable and renewable products and materials. For that reason lignin needs to be further analyzed although the various challenges this process implicates. The major obstacles in this field are lignin’s chemical heterogeneity, all the modifications in lignin’s chemical structure owing to its extraction method and purification process and the lack of appropriate standards that match lignin’s structure. However, significant breakthroughs have been made in this area of research and have yielded more knowledge on lignin’s chemical composition remaining the molecular weight (MW) distribution as a task. This present work aims to study the characterization of the high MW of Kraft lignin using Size Exclusion... (More)
- The valorization of lignin offers sustainable and renewable products and materials. For that reason lignin needs to be further analyzed although the various challenges this process implicates. The major obstacles in this field are lignin’s chemical heterogeneity, all the modifications in lignin’s chemical structure owing to its extraction method and purification process and the lack of appropriate standards that match lignin’s structure. However, significant breakthroughs have been made in this area of research and have yielded more knowledge on lignin’s chemical composition remaining the molecular weight (MW) distribution as a task. This present work aims to study the characterization of the high MW of Kraft lignin using Size Exclusion Chromatography (SEC) and polystyrene standards (PS) and finding the best separations conditions such as temperature, flow rate and an eluent that can give a good resolution. The yielded molecular weight distribution for lignin was estimated to be in the ranges of 5000-1000 g/mol and 580-370 g/mol at approximately 30°, THF 1 mL/min. (Less)
- Popular Abstract
- Lignin is the second most abundant polymer found on earth after cellulose. This polymer constitutes a main component in the cell wall of the plants and works as a mechanical backbone providing shape, stability and rigidity. In addition, due to lignin’s chemical composition offers a wide range of applications as biodegradable plastics, textile, lubricants, composites, pesticides and many other products. Lignin has the potential to be a great substitute for petroleum based fuel and materials. Therefore, more knowledge on lignin’s properties is needed. One important property that the research community is trying to determinate is lignin’s molecular weight (MW) which implicates a big challenge. Because the chemical composition of lignin is... (More)
- Lignin is the second most abundant polymer found on earth after cellulose. This polymer constitutes a main component in the cell wall of the plants and works as a mechanical backbone providing shape, stability and rigidity. In addition, due to lignin’s chemical composition offers a wide range of applications as biodegradable plastics, textile, lubricants, composites, pesticides and many other products. Lignin has the potential to be a great substitute for petroleum based fuel and materials. Therefore, more knowledge on lignin’s properties is needed. One important property that the research community is trying to determinate is lignin’s molecular weight (MW) which implicates a big challenge. Because the chemical composition of lignin is highly complex and varies owing to its botanical origin. Moreover, lignin’s structure become substantially modified during its extraction and purification. Being Kraft lignin the type of lignin gained from the Kraft pulping process in the paper industry. Different analytical methods have been used for this purpose and we have more knowledge on lignin’s structure and its constituents but there is no gold standard method that can be used to elucidate the MW.
In the present study we aim to characterize the MW distribution of lignin using Size Exclusion Chromatography (SEC). This analytical technique is used because it is an unquestionable powerful method for polymer studies and it works over a wide range of high molecular weights. This method is based on the separation of the sample molecules according to their size or the volume that they occupied as dissolved molecules. The sample solution passes through a column filled with porous packing material, called the stationary phase and the fluid that carries on all sample molecules is called the mobile phase. Because the sample molecules have different sizes, some of them are able to enter the pores while other just flush out with the mobile phase. In this manner the separation is effectively performed. Since there are some factors that affect the separation it is important to take those in account. This work was aimed to study the type of solvent, temperature, flow rates, calibration standards and the interactions that may occur between the sample and phases. The results in this investigation have shown that Tetrahydrofuran (THF) is a good solvent for the separation of Kraft lignin samples, working best at 1.0 mL/min in 30°C, giving a molecular weight distribution 5000-1000 mg/mol and 580-370 mg/mol. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9042974
- author
- Meuller, Cecilia LU
- supervisor
- organization
- course
- KASM01 20202
- year
- 2021
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Kraft lignin, molecular weight, polystyrene standard, Size Exclusion Chromatography and THF, technical analytical chemistry
- language
- English
- id
- 9042974
- date added to LUP
- 2021-04-15 10:56:44
- date last changed
- 2021-04-15 10:56:44
@misc{9042974,
abstract = {{The valorization of lignin offers sustainable and renewable products and materials. For that reason lignin needs to be further analyzed although the various challenges this process implicates. The major obstacles in this field are lignin’s chemical heterogeneity, all the modifications in lignin’s chemical structure owing to its extraction method and purification process and the lack of appropriate standards that match lignin’s structure. However, significant breakthroughs have been made in this area of research and have yielded more knowledge on lignin’s chemical composition remaining the molecular weight (MW) distribution as a task. This present work aims to study the characterization of the high MW of Kraft lignin using Size Exclusion Chromatography (SEC) and polystyrene standards (PS) and finding the best separations conditions such as temperature, flow rate and an eluent that can give a good resolution. The yielded molecular weight distribution for lignin was estimated to be in the ranges of 5000-1000 g/mol and 580-370 g/mol at approximately 30°, THF 1 mL/min.}},
author = {{Meuller, Cecilia}},
language = {{eng}},
note = {{Student Paper}},
title = {{Molecular weight determination of Kraft lignin samples by Size Exclusion Chromatography}},
year = {{2021}},
}